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<title>Using as: Symbol Value</title>

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Next: <a href="Symbol-Type.html#Symbol-Type" accesskey="n" rel="next">Symbol Type</a>, Up: <a href="Symbol-Attributes.html#Symbol-Attributes" accesskey="u" rel="up">Symbol Attributes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Value"></a>
<h4 class="subsection">5.5.1 Value</h4>

<a name="index-value-of-a-symbol"></a>
<a name="index-symbol-value"></a>
<p>The value of a symbol is (usually) 32 bits.  For a symbol which labels a
location in the text, data, bss or absolute sections the value is the
number of addresses from the start of that section to the label.
Naturally for text, data and bss sections the value of a symbol changes
as <code>ld</code> changes section base addresses during linking.  Absolute
symbols&rsquo; values do not change during linking: that is why they are
called absolute.
</p>
<p>The value of an undefined symbol is treated in a special way.  If it is
0 then the symbol is not defined in this assembler source file, and
<code>ld</code> tries to determine its value from other files linked into the
same program.  You make this kind of symbol simply by mentioning a symbol
name without defining it.  A non-zero value represents a <code>.comm</code>
common declaration.  The value is how much common storage to reserve, in
bytes (addresses).  The symbol refers to the first address of the
allocated storage.
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